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Tutorial: Equation driven sketching with DSM

This is a tutorial to get you started with using mathematical equations to sketch curves and makes surfaces/solids using them. You will need version 5.0 or newer of DesignSpark Mechanical to access this advanced sketch mode.

Now, let's get started with the tutorial:

Here is the syntax and list of pre-defined functions::

  • Parameters include a name and are enclosed in square brackets [L]
  • Functions include a function name followed by parenthesis containing any values as arguments
    • For example: Sine([t]-[r])
  • The table below shows common predefined intrinsic functions included

A full list of mathematical expressions including operators & constants is given in the main help documentation: http://help.spaceclaim.com/dsm/5.0/en/Content/MathematicalExpressions.htm

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Here's another example of a group of equations to define a symmetric airfoil using the NACA scheme. Give it a try!

This is a NACA 0015 airfoil where the trailing digits '15' means the airfoil has a 15% thickness to chord length ratio ([a] in below equations). Design units were Metric.

Upper surface of airfoil:

x

([t])

y 5*([a])*((0.2969*Sqrt([t]))-(0.1260*[t])-(0.3516*Pow(([t]),2.0))+(0.2843*Pow(([t]),3.0))-(0.1036*Pow(([t]),4.0)))
z 0
Interval(t) Start:0, End:1, Scale:50
a 0.15

Lower surface of airfoil:

x

([t])

y -5*([a])*((0.2969*Sqrt([t]))-(0.1260*[t])-(0.3516*Pow(([t]),2.0))+(0.2843*Pow(([t]),3.0))-(0.1036*Pow(([t]),4.0)))
z 0
Interval(t) Start:0, End:1, Scale:50
a 0.15

NACA_0015_airfoil_equation.PNG

mceclip0.png

You could change the above equations to build a cambered airfoil, which is used in real world aircraft. Eg. a supercritical NACA 2412 used in A380s. The leading digits '24' indicate the degree of camber.

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